1. Field of the Invention
The present invention relates to a motor-operated film driving device for cameras which performs automatic film winding upon completion of exposure of each frame thereof and further automatic film rewinding upon completion of exposure of all the frames thereof.
2. Description of the Prior Art
In a motor-operated automatic film winding device the motor is forced to stop when the film winding is inhibited upon completion of exposure of all film frames with resultant over-tension of the wound-up film. The motor torque then increases gradually with increasing motor current and the film is ruptured when the torque has exceeded the film's critical strength. This causes a waste of electric power as well. As a countermeasure therefor there is a known device which detects the increase of the motor current due to the forced stoppage of the motor or the increase of the tention of the film for interrupting power to the motor or warning of the using-up of the film. Any of these devices however, are directed only to such detection, relating in no case to procedures after the motor stoppage or the provision of a warning.